The timing of the announcements is coincidental, but also a sign that privacy is an important arena in which platform vendors must compete today.

One theme was common to both companies' explanations: They want you to know that they emphatically do not read your email in order to target advertising.

"We don’t use what you say in email, chat, video calls or voice mail, or your documents, photos or other personal files to choose which ads to show you," was how Microsoft put it.

Apple was more succinct, but couldn't resist a little jab at Google: "Some companies mine your cloud data or email for personal information to serve you targeted ads. We don’t."

It's a key point, and one that Apple made more explicitly elsewhere: while both it and Microsoft sell their operating systems, Google gives away Chrome OS and Android. But setting them up requires a Google account, complete with a Gmail address the company can monitor to sell targeted advertising.

No targeted advertising doesn't mean no information collection, though, and both Microsoft and Apple admit to collecting information about the users of their software: In fact, their new privacy explanations go into excruciating detail about the kind and quantity of information they collect, and how it allows them to help their customers.

Microsoft mentions a few times in passing that it avoids collecting personally identifying information, but Apple really goes to town on its explanations of how it tries to protect privacy.

Mapping is a case in point: Where Microsoft just says it needs to know where you are in order to provide you with directions, Apple sees a chance for differentiation -- and another dig at Google: "Other companies try to build a profile about you using a complete history of everywhere you’ve been, usually because they’re targeting you for advertisers." It then goes on to explain how, when it gives directions, it chops the route up into small chunks linked only by a random identifier, and throws away the first and last parts so no one with access to the route planning history can work out who you are or where you live.

Who would have access to that history is another part of the story, and one to which Apple devotes a full third of its new privacy pages, under the heading "Government information requests."

If companies want to allay customers' fears of the cloud, they are going to have to follow Apple and Microsoft in making their data collection much less opaque.

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